Title :
A Compact On-Chip Capacitive-Coupling Scheme for Very-Low Frequency Applications
Author :
De Lima, Jader A.
Author_Institution :
Brazil Semicond. Technol. Center, Freescale Semicond.
Abstract :
An active capacitive-coupling scheme (ACCS) that fixes the common-mode voltage by means of a servo-amplifier and a drain-common transistor on a feedback loop is presented. Since the input current is limited to junction leakage, the ACCS equivalent resistance is extremely high, so that break-frequencies in the sub-Hertz range can be attained for on-chip coupling capacitors. The ACCS and a voltage preamplifier were prototyped using a 0.8mum CMOS process and a 1.8V-supply. Measured cut-off frequency is 0.64Hz, for a 33pF-coupling capacitor, so that the ACCS emulates an equivalent resistor of 7.53GOmega THD is -50dB for 164mV-ouput amplitude.
Keywords :
CMOS integrated circuits; capacitors; circuit feedback; preamplifiers; 0.64 Hz; 0.8 micron; 1.8 V; 33 pF; 7.53 Gohm; CMOS process; active capacitive-coupling scheme; common-mode voltage; drain-common transistor; feedback loop; on-chip coupling capacitors; servo-amplifier; voltage preamplifier; CMOS process; Capacitors; Cutoff frequency; Electrical resistance measurement; Feedback loop; Frequency measurement; Preamplifiers; Prototypes; Resistors; Voltage;
Conference_Titel :
Circuits and Systems, 2007. ISCAS 2007. IEEE International Symposium on
Conference_Location :
New Orleans, LA
Print_ISBN :
1-4244-0920-9
Electronic_ISBN :
1-4244-0921-7
DOI :
10.1109/ISCAS.2007.378216
